Hello, I have this tall (5-6 feet, or 150-180cm) weed growing in my garden in Ithaca, NY, USA. I think it's wild amaranth, but I am not sure. If it is, is there an easy way to identify which specie? If not, what do you think it is? I attach some pictures of the general look, and details of leaves, stem and flowers. Thank you in advance for your help in indentifying this plant. Olivier